1. Field of the Invention
The present invention relates to pourable fatty dispersions consisting of a triglyceride oil in which a non-fat phase is dispersed and which dispersion further contains a stabilising amount of triglyceride fat. A preferred fatty dispersion is liquid margarine.
2. The Related Art
Margarine consists of a continuous fat phase and an aqueous phase which is dispersed as fine droplets in the fat phase. In contrast to common margarine which has a semi-solid, plastic, spreadable consistency, liquid margarine is pourable at ambient temperature.
All margarine fat consists of a mixture of a fat which at ambient temperature is fully liquid (an oil), and a fat which is solid at ambient temperature, the so-called hardstock fat which has stabilising functionality. The ratio of liquid and solid fat is chosen such that after proper processing together with an aqueous phase a product with a suitable plastic consistency is obtained. In common margarine the crystals of the solid fat form a network throughout the liquid oil resulting into a structured fat phase. The aqueous phase droplets are fixed within the spaces of the lattice of solid fat crystals. In this way coalescence of the droplets and separation of the heavier aqueous phase from the fat phase is prevented. Wrapper margarines need more solid fat than tub margarines and tub margarines need more than liquid margarines. Moreover, liquid margarines need a different kind of stabilising fat.
The presence of hardstock fat aims to stabilise the margarine emulsion. Unstable liquid margarines show phase separation. Phase separation, particularly oil exudation, becomes visible as a layer of oil on the surface of the liquid margarine.
It is desired that a stable liquid margarine of good quality is substantially free from oil exudation, yet exhibits good pourability. It is difficult to combine good stability with good pourability. The solid fat crystals are needed for the stability of the emulsion, but on the other hand may adversely affect its pourability. Liquid margarine manufacture therefore requires a hardstock fat with properties which are delicately balanced.
The problem of preparing a satisfactory liquid margarine has been addressed years ago as evidenced by the following patent documents: U.S. Pat. No. 3,595,674, SU 553964, JP 51133453, U.S. Pat. Nos. 5,756,142, 3,338,720, 4,446,165, 4,341,812, GB 1092236.
Although prior art mentions several fully hydrogenated fats for use as liquid margarine hardstock fat, there is seldom found any specification of their performance. Generally, vaguely defined mixtures of fully hydrogenated fats are included in such prior art references, however, without specification of type of fats, blend ratios or performance.
Table I shows the poor performance of some common margarine hardstock fats when applied in a liquid margarine.
Stability is measured by an oil exudation test and pourability by the Bostwick test. The standard for stability is an oil exudation rating being 2 or less and the standard for pourability is a Bostwick value being at least 15.
A liquid margarine having a pourability rating  less than 15 is too thick and lacks acceptable pourability.
An oil exudation rating  greater than 2 points to an unacceptable inhomogeneous product appearance and bad kitchen performance.
Both tests and a general liquid margarine preparation are described later in the specification.
Hence in the context of the present specification an emulsion, or, generally, a fatty dispersion is pourable and stable when it complies with the above standards.
Fully hydrogenated high erucic rapeseed oil (shortly denoted as fully hardened rapeseed oil or RPh70) has appeared to be the only hardstock fat which complies with the above standards. It is widely used for the manufacture of satisfactory liquid margarines which combine good stability with good pourability. Presently, from all above mentioned fats solely fully hardened rapeseed oil is employed for the preparation of high quality liquid margarine. Its use is described e.g. in U.S. Pat. No. 5,756,142.
RPh70 is unrivalled as hardstock fat also for use in other pourable fatty dispersions consisting of a triglyceride oil in which a non-fat phase is dispersed. WO 98/47386, for example, deals with the stabilisation of a pourable fatty dispersion containing herbs as the dispersed phase. Besides RPh70, other fats are mentioned as possible hardstock fat: hardened sunflower seed oil, hardened soybean oil, hardened palm oil, hardened cottonseed oil or mixtures thereof. Besides RPh70 only hardened sunflower seed oil has been exemplified. The product is said to have xe2x80x9cacceptable propertiesxe2x80x9d.
Generally, liquid margarines are prepared with 2-5 wt. % of hardstock fat on total fat phase.
RPh70 may be unsurpassed as liquid margarine hardstock fat, its use also has less favourable aspects. Rph70 is derived from a fat with a high erucic acid content. From a nutritional point of view erucic acid should be avoided in food compositions. Hydrogenation of the unsaturated erucic acid does not fully remedy this. Another drawback of Rph70 is its high price.
Besides that, liquid margarine hardstock fats are wanted which have a stability and pourability performance which is better than what Rph70 can offer.
We have discovered the parameters which define well performing hardstock fats to be used for the manufacture of liquid margarines. First it was found that for proper performance such fats should solidify as small mixed crystals rather than as an extended fat crystals lattice such as is needed for the plastic consistency of common margarines.
Then, the conditions for the formation of such mixed crystals have been found to be related in a specific way to the amount and the nature of the triacylglycerides (TAGs) which constitute the hardstock fat.
The present invention provides a hardstock fat suited for stabilizing a pourable dispersion of a non-fat phase in a triglyceride oil, which hardstock fat consists of a mixture of triglycerides, characterized in that,
at least two triglycerides having a melting point  greater than 55xc2x0 C. each have a concentration of at least 5 wt. %,
the amount of triglycerides having fatty acid residues with a difference in chain length of the longest and the shortest residue being at least four carbon atoms is at least 15 wt. % and
the amount of triglycerides having a melting point of 25-55xc2x0 C. is xe2x89xa625 wt. %.
Fully hardened high erucic rapeseed oil (Rph70 ) fulfills the conditions of this definition. This fat has been found earlier by chance and is an isolated representative of the group of invented fats. Because it is known, Rph70 is excluded from the invention by a disclaimer.
The invention comprises also liquid margarines and other pourable fatty dispersions containing hardstock fat and which fat is comprised in the invention.